ALTITUDE_CLAMPED_TO_SEA_FLOOR: the altitude value is
ignored and the feature or view is placed on the sea floor.

ALTITUDE_RELATIVE_TO_SEA_FLOOR: the altitude value is
calculated relative to the height of the sea floor at that geographic
point.

Examples

Absolute altitude mode

Absolute altitude modes are calculated from sea level. To place an
object underwater, specify a negative altitude value. A negative altitude
over land will place the object below the Earth's surface. Objects below the
Earth's surface cannot be viewed or clicked.

Clamped to sea floor

Clamping an object to the sea floor positions it on the bottom of a
major body of water, if underwater terrain information is available. If no
terrain information is available, CLAMP_TO_SEA_FLOOR behaves as
CLAMP_TO_GROUND, and the object will be placed on the surface. This altitude
mode ignores any altitude values specified for the object.

In the example below, each point of the polygon has an altitude value
specified; note how the altitude is ignored in the rendered polygon.

Relative to sea floor

Objects that are placed relative to the sea floor, when located over a major
body of water for which underwater terrain information is available, have
their altitude calculated from the floor of that body of water. If placed
over land or over water for which terrain information is not available, the
altitude is calculated from the surface level, as with
ge.ALTITUDE_RELATIVE_TO_GROUND.